Build It Right: Bracing Walls for Wind

Complexity's Poster Child: The 2009 IRC rules on wall bracing for wind are four times lengthier than 2006's. Some dislike all the new choices. Others say they're needed.

One of the biggest trends affecting builders over the past decade has been the relentless growth of government regulation, including ever more complex and comprehensive building codes. But the effort to regulate evolving building practices doesn't always toe a straight line. Take, for example, wall bracing for wind resistance.

On April 25, Pennsylvania Gov. Tom Corbett signed Act 1 of 2011, a law amending the commonwealth's building code. While most of the press focused on the law's repeal of the fire sprinkler mandate for one- and two-family homes, just as significant for builders was its exemption of Pennsylvania from the 2009

International Residential Code (IRC) wall-bracing provisions. The bracing provisions, which had been adopted 16 months earlier, had generated vocal opposition from builders and designers.

"They ranked second only to sprinklers in the number of complaints we got," says Jerry Leach, director of building codes for the Pennsylvania Builders Association. The provisions had grown from seven pages in 2006 to 28 pages of text and diagrams in 2009, and opponents called them unnecessarily complex. Act 1 reinstated the 2006 code.

But after the law passed, Leach was reminded that the code-making process is a tug-of-war between competing interests.

"I got calls from people who liked the '09 bracing provisions," he recalls. "Yes, they were more complex, but they also allowed for more design flexibility."

The need for bracing is nothing new: Codes have long required that walls have some built-in racking resistance (i.e., features to withstand forces that would distort walls from their rectangular shape), whether from diagonal let-in braces or plywood panels. The 2009 IRC's section 602.10 expanded this requirement by providing a series of pre-engineered bracing options in areas with design wind speeds of 110 mph or less, which is most of the United States. The IRC now includes 13 bracing methods and allows builders to mix and match methods, while the 2006 code offered eight bracing options and was unclear on mixing and matching. The 2009 version also provides more leeway on where bracing panels can be located.

Harry Whitver / www.whitver.comBRACE YOURSELF FOR CHANGE: The 2009 International Residential Code offers more choices in how to brace a wall, but at the price of more complexity. Builders can now offset braced wall panels from braced wall lines, and they have more options for where to place those panels. Permissible offsets and spacings depend on a number of design factors spelled out in the code--one reason for its increased length.

The 2009 changes give designers and builders more design flexibility, but some of them say the complexity of these provisions, and the lack of a simple way to navigate them, encourage mistakes. "Every year the code becomes more difficult to comprehend and comply with, and the bracing requirements are the poster child for this trend," says James Wentling, a Philadelphia-based architect who works with home builders in several states. "This added complexity causes confusion and misunderstandings between designers, code officials and builders. I've seen [the bracing requirements] done correctly in the field maybe once."

Members of the International Code Council's Wall Bracing Committee say that changes in home design and construction made this complexity unavoidable. "We're building much different homes than in the past," says Jay Crandell, principal of ARES Consulting in West River, Md. "There had been four to five decades of lack of work in this area. During that time, houses grew in size and complexity, increasing structural loads and decreasing [wall] strength by a factor of six to eight." He says that with previous code versions, standards written for small, single-story tract homes were being applied to 12,000 square-foot McMansions with large expanses of glass. It wasn't working.</div><div class="articlepage">

Crandell also insists that IRC's bracing provisions aren't as onerous as some have painted them. "One reason [the bracing section] is so long is that there are lots of figures to explain things that weren't explained in the past," he says. "This gets lost in the page-count approach."

Another problem with the old code was that its wind-bracing requirements weren't backed by research. "When the original IRC was written in 2000, the bracing provisions were based primarily on seismic loads," says Edward Keith, a senior engineer with APA-The Engineered Wood Association. "When it came to covering wind, they tried to force-fit the seismic provisions into a high-wind context with doubtful accuracy. This was done simply because of limited time." He says one reason the 2009 bracing section is so long is that it defines the requirements for seismic and wind.

For those who want to delve deeper into the subject, Keith co-authored APA's "Guide to 2009 IRC Lateral Bracing Provisions" (on sale at www.apawood.org). Containing more than 250 pages, it explains the science behind the bracing provisions, outlines differences between the 2006 and 2009 codes, and gives examples of how to do bracing in different situations. "If you read it, you will know as much about bracing as the committee," he says.

Most builders and designers will be glad to hear that more requirements don't seem to be on the horizon. Both Crandell and Keith say the goal during the next few code cycles will be to clarify the current provisions so that they're easier to follow.

A simplified, four-page bracing standard for the typical starter home with simple geometry has been approved for the 2012 code revision, and people are already anticipating the code cycle after that. Says Keith: "For 2015 we're looking at ways to make the requirements more workable and more usable."